#include <stdio.h>
#include <math.h>
double func(int a){
    double b = a - sin(a) - cos(a);
    return b;
}
int  main(){
    double max = 0;int i;
    for (i = 1; i < 21; ++i) {
        double b = func(i);
        if(b > max){
            max = b;
        }
    }
    printf("%f", max);
    return 0;
}
